Cooperative research in the pediatric cancer groups has been a major factor in the greatly improved cure rate in childhood cancers. Because most childhood cancers are rare, it is only through this mechanism that adequate numbers of patients can be accrued in reasonable lengths of time for randomized controlled studies. The Department of Pediatrics at Roswell Park Memorial Institute has actively participated in the Pediatric Oncology Group (POG) to answer treatment questions which would be impossible to answer were we to conduct only single institution studies. Some pediatric solid tumors are so uncommon that intergroup studies are required. We are participating in these studies, specifically, the National Wilms' Tumor Study, the Intergroup Ewing's Sarcoma Study, the Intergroup Rhabdomysarcoma Study and the Intergroup Hodgkin's Disease Study. We are also strongly committed to interdisciplinary approach to pediatric cancer and have a good working relationship with the necessary cooperating specialities including Radiation Medicine, Pediatric Surgery, Pediatric Neurology, Neurosurgery and Orthropedic Surgery, and basic research in viral oncology, immunology and pharmacology. As more children are cured from their cancer, the identification and prevention, when feasible, of complications of therapy has become important. We are actively involved in this area, with our major interest in controlled studies of long-term irreversible toxicities of radiation therapy and chemotherapy on the CNS of children with ALL. We are investigating the suppressive effects of chemotherapy on the immune gamma interferon response raising the possibility of specific gamma interferon therapy for severe viral infections in these cancer patients. We are also evaluating the acute and long-term effects of radiation therapy and chemotherapy on various committed stem cell pools of peripheral blood and bone marrow.